From owner-freebsd-net@freebsd.org Sat Nov 7 11:26:10 2015 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4EE37A2750C for ; Sat, 7 Nov 2015 11:26:10 +0000 (UTC) (envelope-from brde@optusnet.com.au) Received: from mail105.syd.optusnet.com.au (mail105.syd.optusnet.com.au [211.29.132.249]) by mx1.freebsd.org (Postfix) with ESMTP id 054601336 for ; Sat, 7 Nov 2015 11:26:09 +0000 (UTC) (envelope-from brde@optusnet.com.au) Received: from c211-30-166-197.carlnfd1.nsw.optusnet.com.au (c211-30-166-197.carlnfd1.nsw.optusnet.com.au [211.30.166.197]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 6935D104592A; Sat, 7 Nov 2015 22:26:07 +1100 (AEDT) Date: Sat, 7 Nov 2015 22:26:06 +1100 (EST) From: Bruce Evans X-X-Sender: bde@besplex.bde.org To: Ian Smith cc: Rasool Al-Saadi , Hans Petter Selasky , Luigi Rizzo , "freebsd-net@freebsd.org" , Bruce Evans Subject: RE: Timing issue with Dummynet on high kernel timer interrupt In-Reply-To: <20151107155144.I12989@sola.nimnet.asn.au> Message-ID: <20151107220450.X1692@besplex.bde.org> References: <6545444AE21C2749939E637E56594CEA3C0DCCC4@gsp-ex02.ds.swin.edu.au> <5638B7B5.3030802@selasky.org> <6545444AE21C2749939E637E56594CEA3C0DE7FF@gsp-ex02.ds.swin.edu.au> <563B2703.5080402@selasky.org> <6545444AE21C2749939E637E56594CEA3C0E0BD9@gsp-ex02.ds.swin.edu.au> <563C6864.2090907@selasky.org> <563C786C.1050305@selasky.org> <563CC186.9000807@selasky.org> <6545444AE21C2749939E637E56594CEA3C0E1B79@gsp-ex02.ds.swin.edu.au> <20151107155144.I12989@sola.nimnet.asn.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.1 cv=cK4dyQqN c=1 sm=1 tr=0 a=KA6XNC2GZCFrdESI5ZmdjQ==:117 a=PO7r1zJSAAAA:8 a=JzwRw_2MAAAA:8 a=kj9zAlcOel0A:10 a=JGmdEZ7-IIC20yNyzecA:9 a=CjuIK1q_8ugA:10 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 07 Nov 2015 11:26:10 -0000 On Sat, 7 Nov 2015, Ian Smith wrote: > ... > I also notice that with HPET, the timer interrupts themselves, whether > as few as 60-70/s idle in one-shot mode or ~2000/s in periodic, appear > in systat -vm or vmstat -w10 'Int' column, whereas with LAPIC or (yes I > even tried) i8254, these timer interrupts don't count in that column. Interrupt reporting is mostly broken for "fast" interrupts. E.g., systat -v counts them in the Interrupts column (separate and Total) but not in the Int summary; vmstat -m doesn't count them anywhere (it shows the Int summary). vmstat -i shows them much like the Interrupts column in systat -v (except it actually displays them all when there are too man CPUs or Interrupts to fit in systat -v). I use COUNT_IPIS and COUNT_XINVLTLB. The interrupts counted by these are actually fast. These mess up the systat -v display by giving too many active interrupts to display for just a couple of CPU. systat -v tends to display these in preference to more interesting interrupts. vmstat -i displays these too. "fast" and fast interrupts should be counted separately and are probaly best left out of the Int summary. They should also be displayed separately. > I'll try Hans' suggestion of adjusting in loader.conf, rebooting between > various options if really needed, though that'll be far more tedious .. > [ I've just now seen Bruce's latest, so maybe I haven't been doing the > wrong thing playing with these after all? ] The eventtimer choice is readonly, so rebooting seems to be required to change it. Too much like Windows. I often miss being able to change hz. Event timers now do much more complicated changes than that. They implement a sort of dynamic hz, but still use the boot-time hz as a default. Bruce